A few days ago I've upgraded from Kubuntu 14.10 to 15.04 (yes, I've waited a long time before doing this...). Somehow since the upgrade Kubuntu has started reminding me that there's problem downloading the flash-plugin installer. I don't care about that because I use the pepperflash/freshplayer system and I don't need the flash-plugin installer which is outdated anyway so I've dismissed the message. However the message returns at each boot. I've dismissed it each time but it seems I can't get rid of it permanently. How do I solve this?